Question

tính

1)  \(\lim\limits_{n\rightarrow\infty}\dfrac{3n^2+5n-3}{-n+5}\)

2)  \(\lim\limits_{n\rightarrow\infty}\dfrac{-7n^2+4}{-n+5}\)

3)  \(\lim\limits_{n\rightarrow\infty}\dfrac{-3n^2+2}{n-2}\)

Answer 1

1) \(\lim\limits_{n\rightarrow\infty}\dfrac{3n^2+5n-3}{-n+5}\)

\(=\lim\limits_{n\rightarrow\infty}\dfrac{n\left(3n+5-\dfrac{3}{n}\right)}{-n\left(1-\dfrac{5}{n}\right)}\)

\(=\lim\limits_{n\rightarrow\infty}\dfrac{3n+5-\dfrac{3}{n}}{-\left(1-\dfrac{5}{n}\right)}\)

\(=\left[{}\begin{matrix}-\infty\left(n\rightarrow+\infty\right)\\+\infty\left(n\rightarrow-\infty\right)\end{matrix}\right.\)

Bài 2,3 tương tự, bạn tự làm nhé!